JP2000347050A - Optical transmitting/receiving module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmitting/receiving module which allows the multiple pieces to be manufactured together through a semiconductor process for example and which also facilitates connection with an optical fiber. SOLUTION: The module is constituted of an optical waveguide 6, which is formed on a substrate 1 in a manner matching to the optical fiber F held on an optical fiber guide groove 2a also formed on the substrate 1, and an optical filter arranged in this optical waveguide so as to branch the light of plural wavelengths passing this waveguide 6, with the optical fiber F connected through a half mirror 9 with light receiving elements for each wavelength and light emitting elements which are arranged on the substrate 1; as a result, a number of light transmitting/receiving modules can be manufactured together in bulk through a semiconductor process for example, and also the module facilitates connection with the optical fiber F.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission / reception module used for optical communication, optical signal processing, etc., for converting an optical signal into an electric signal.

[0002]

2. Description of the Related Art Conventionally, bidirectional optical communication using optical fibers has been frequently used in communication equipment, audio equipment, and the like. Generally, a high-speed modulated optical signal is transmitted through an optical fiber. In order to convert this into finally necessary information such as audio and video, it is converted into an electric signal and further converted into audio and video data. Thus, the required output can be obtained. Various methods and optical transmission / reception modules have been proposed. For example, JP-A-8-190026 discloses that a waveguide and a semiconductor device platform are formed on a silicon substrate, and a filter, a laser diode (light-emitting device),
A module mounting a photodiode (light receiving element) and the like is disclosed. Since this module is formed on a substrate by using a process similar to that of a semiconductor device, there is an advantage that a large number of modules can be collectively formed on a wafer.

[0003]

However, in the above-described module for forming a waveguide on a substrate, when connecting to an optical fiber, a separate component holding an optical fiber end, such as a fiber array, is prepared and highly accurate. The connection has to be performed using the alignment technique, and the operation is complicated. In fact,
Optical axis adjustment requires accuracy higher than ± 0.5 μm,
It is a very cumbersome task. In addition, in the above structure, the signal light of 1.55 μm, which is the signal light only for downlink, is reflected by the filter and then re-coupled to the waveguide. The incident light is converted into an electric signal. This increases the number of connection parts, causes an increase in light loss, and lowers the transmission speed.

Therefore, for example, Japanese Patent Application Laid-Open No. 10-197762
In Japanese Patent Application Laid-Open Publication No. H10-157, a module in which an optical fiber is directly assembled to a substrate without using a waveguide is also proposed. In the case of this module, there is an advantage that a high-precision alignment operation can be omitted because it is not necessary to separately connect the optical fiber.

[0005] However, since the optical fiber is already incorporated in a state where the module is assembled and mounted, not only may the fiber be erroneously damaged during the process, but also the optical fiber protrudes from the module. In addition, there is a problem that assembly must be performed individually, a large space is required, and collective processing such as a case of forming a waveguide on a substrate cannot be performed at a time. In addition, this structure has many parts,
At the time of positioning each component, if the positional accuracy of each component is not increased, an excessive stress is applied to the fiber, which may degrade its characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides an optical transmitting / receiving module which can be manufactured in large numbers by a semiconductor process or the like and can be easily connected to an optical fiber. The purpose is to:

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided an optical transceiver for transmitting and receiving an optical signal of a first wavelength transmitted over a fiber and receiving an optical signal of a second wavelength. A module for aligning an optical fiber guide groove formed on a substrate made of quartz or silicon (Si) to guide the end of the optical fiber with an end of the optical fiber guided by the optical fiber guide groove; An optical waveguide formed on the substrate, a light emitting element of the first wavelength light disposed on the substrate, and a light emitting element of the first and second wavelengths disposed on the substrate. A light-receiving element, and an optical filter disposed in the optical waveguide on the substrate so as to split light reaching the optical waveguide from the optical fiber into light of the first wavelength and light of the second wavelength. , By the optical filter The light guide on the substrate for guiding the light of the first wavelength to the light receiving element for the light of the first wavelength and for guiding the light of the first wavelength from the light emitting element from the optical waveguide to the optical fiber. This is achieved by providing an optical transceiver module having a half mirror disposed in a wave path. In particular, the optical filter is inserted into a slit formed obliquely in the optical waveguide on the substrate, and reflects the light of the second wavelength toward a light receiving element on the substrate. The half mirror is inserted into a slit formed obliquely in the optical waveguide on the substrate, and the light of the first wavelength split by the optical filter is transmitted to a light receiving element on the substrate. It is preferable that the light is reflected toward the optical fiber and the light of the first wavelength of the light emitting element is guided from the optical waveguide to the optical fiber.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of an optical transceiver module to which the present invention is applied, and FIG. 2 is a sectional view thereof. This optical transmitting / receiving module includes a connection section 2 for connecting to an optical fiber, a first receiving section 3 for receiving light having a first wavelength of 1.31 μm, for example, and a transmitting section 4 for transmitting light having a first wavelength. For example, the second receiving unit 5 for receiving the light of the second wavelength of 1.55 μm and the second receiving unit 5 are formed on the same substrate 1 made of quartz or silicon.

The optical fiber connecting portion 2 comprises a guide groove 2a having a V-shaped cross section formed in front of a step portion 1a provided on the substrate 1, and an external optical fiber F is inserted into the guide groove 2a. Accept and hold the tip.

The second receiving section 5 is a part of the light passing through the optical waveguide 6 penetrating through the step portion 1a of the substrate 1 so as to coincide with the axis of the optical fiber F held in the guide groove 2a. The reflection type optical filter 7 inserted obliquely in the middle part of the optical waveguide 6 so as to reflect only the wavelength (1.55 μm) component obliquely upward in the figure, and the light reflected by the optical filter 7 And a photodiode 8 as a light receiving element for receiving light of the second wavelength provided on the step portion 1a for receiving light.

The first receiving section 3 reflects the light passing through the optical filter 7 among the light passing through the optical waveguide 6, that is, the first wavelength (1.31 μm) component obliquely upward in the drawing. A half mirror 9 obliquely inserted into the intermediate portion of the optical waveguide 6, and a light receiving element of a first wavelength light provided on the stepped portion 1a for receiving the light reflected by the half mirror 9. And a photodiode 10.

The transmitting section 4 is provided on the side opposite to the optical fiber F with the step section 1a interposed therebetween, that is, behind the step section 1a, the light of the first wavelength provided so as to face the end of the optical waveguide 6 directly. It comprises a laser diode 11 as a light emitting element and a monitoring photodiode 12 for monitoring the output of the laser diode 11.

Hereinafter, a description will be given of a manufacturing procedure of the above-mentioned optical transceiver module. First, a step (platform) is formed on a quartz substrate or a silicon wafer by etching or machining. Next, a lower cladding layer 6a of SiO ₂ or the like is formed by a film forming method such as a CVD method, and is planarized by polishing or etching to a predetermined thickness.

Next, a core layer 6b is formed on the lower cladding layer 6a.
Is formed. Here, the core layer 6b has a refractive index slightly higher than that of the lower cladding layer 6a and the upper cladding layer 6c described later in order to propagate light of a communication wavelength.
It is generally known to add a small amount of an element such as Ge or Ti in order to increase the refractive index similarly to the optical fiber.

Next, in order to form an optical waveguide path, that is, a core pattern, a resist is formed using a photomask prepared in advance, and then the core layer 6b is etched (photolithography). Here, RIE (reactive ion etching) is preferably used for the etching. At this time, by forming a pattern for forming the V-shaped guide groove 2a serving as a reference for positioning the optical waveguide 6 and the optical fiber F on the photomask, the resist can be simultaneously formed. it can. For this reason, the relative displacement between the core layer 6b of the optical waveguide 6 and the optical fiber guide groove 2a does not substantially occur because the same photomask is used.
The guide groove 2a is made of, for example, KOH
It is preferable to perform anisotropic etching using an alkaline solution. Then, an SiO ₂ film is formed as the upper cladding layer 6c, and the embedded optical waveguide 6 is completed.

After that, the upper cladding layer 6c is planarized, and the upper cladding layer, the core,
By removing the lower cladding layer and the like, the substrate surface before and after the step portion 1a is exposed. Then, an electrode pattern, a wiring pattern, or the like of Au, Al, or the like is formed on the substrate or the upper clad layer 6c as necessary, and the electrodes are dipped with solder.

Next, grooves 13a and 13b for inserting the optical filter 7 and the half mirror 9 and grooves 14 where the optical fiber F abuts against the optical waveguide 6 are formed by dicing or etching. Here, grooves 13a and 13 for inserting optical filter 7 and half mirror 9 are provided.
b is not perpendicular to the surface of the substrate corresponding to the direction of reflection by the optical filter 7 and the half mirror 9, but is formed obliquely at an angle θ of, for example, 8 ° to 30 °. Also,
The groove 14 is formed perpendicular to the substrate so that the end face of the optical fiber F and the end face of the optical waveguide 6 face each other.

Next, the laser diode 11, the photodiodes 8, 10, 12 and other semiconductor elements (not shown) are mounted at predetermined positions by soldering, and the optical filter 7 and the half mirror 9 are inserted into the grooves 13a, 13b, respectively. Add the adhesive and cure. Here, depending on the position and size of the optical filter 7, the half mirror 9, and the photodiodes 8 and 10, each of them may interfere. Therefore, unnecessary portions of the optical filter 7 and the half mirror 9 may be removed as shown in FIG. 3, and as shown in FIG.
If the photodiodes 8 and 10 are mounted via the spacers 15 whose optical path portions are cut out, the light receiving position can be adjusted without removing unnecessary portions of the optical filter 7 and the half mirror 9. FIG. 5 shows an example of the structure of the spacer 15. The spacer 15 has a U-shape having a hollow portion 15a by hollowing out a portion where an optical path is formed at an intermediate portion.

If the spacer 15 itself or its surface is made of a conductive material, it can be electrically connected to the substrate 1. The material of the spacer 15 to be used is, for example, a metal plate such as phosphor bronze or stainless steel plated with gold. Also, if the spacer 15 is interposed, the light path becomes longer from the optical waveguide 6 to the photodiodes 8 and 10, so that the beam spreads and the light receiving efficiency may decrease. The thickness of the spacer 15 is set to 10 in relation to the diameter of the portion.
There is no problem when the thickness is within about 0 μm to 300 μm.

Finally, the substrate is cut one by one, and the optical fiber F is assembled into the guide groove 2a to complete the optical transceiver module.

The operation of the optical transceiver module according to the present invention will be described below with reference to FIG. This optical transceiver module converts an optical signal sent from the optical fiber F into an electric signal, or converts an electric signal from a telephone or the like into an optical signal and sends it to the optical fiber F.

The first wavelength λ1 (1.31 μm) and the second wavelength
An external optical signal including light of wavelength λ2 (1.55 μm) enters the optical waveguide 6 from the optical fiber F,
The second wavelength λ2 by the optical filter 7 inserted in the middle of
Only the (1.55 μm) component is reflected. Then, the reflected light is emitted toward the surface of the substrate 1. Then, the light is received by the photodiode 8 provided at the emission position, converted into an electric signal, and a predetermined output is obtained.

The light transmitted through the optical filter 7, ie, the first light
The half mirror 9 reflects half of the light of the wavelength λ1 (1.31 μm). Then, the reflected light is emitted toward the surface of the substrate 1. Then, the light is received by the photodiode 10 provided at the emission position, converted into an electric signal, and a predetermined output is obtained.

Here, for efficient reception, the beam center of the reflected light of the optical filter 7 and the center of the light receiving portion of the photodiode 8 are matched, and the beam center of the reflected light of the half mirror 9 and the photodiode 10 are reflected. It is necessary to align the center of the light receiving portion, and for that purpose, the optical fiber F and the optical waveguide 6 need to be aligned with high accuracy. In the optical transceiver module according to the present invention, as described above, the guide groove 2 is used.
Since the optical fiber F guided by the optical fiber a and the optical waveguide 6 are aligned with high precision, the light reflected by the optical filter 7 and the half mirror 9 can be easily realized while the connection with the optical fiber is highly accurate. Can be guided to the light receiving element (photodiode) with a minimum loss.

On the other hand, a first wavelength λ1 (1.3) obtained by converting a predetermined electric signal emitted from the laser diode 11 is used.
1 μm) enters the optical waveguide 6, passes through the half mirror 9 and the optical filter 7, and passes from the optical waveguide 6 to the optical fiber F.
And sends out the necessary signals.

The light of the first wavelength λ1 (1.31 μm) is light used for two-way communication at one wavelength, and prevents the collision of signals with each other by a time division method for controlling the bidirectional oscillation timing. In. Also, the first wavelength λ1
The light of (1.31 μm) loses 50% of the amount of light by the half mirror 9 for both transmission and reception. However, setting the transmission speed in anticipation of this loss does not cause a problem in the system.

[0028]

As is apparent from the above description, according to the optical transceiver module of the present invention, the optical transceiver module is also formed on the substrate so as to match the optical fiber held in the optical fiber guide groove formed on the substrate. And a light receiving element for each wavelength disposed on an optical fiber and a substrate via an optical filter and a half mirror disposed in the optical waveguide to split light of a plurality of wavelengths passing through the optical waveguide. In addition, by adopting a structure for connecting the light emitting element, a large number of optical transmitting and receiving modules can be manufactured collectively by a semiconductor process or the like, and the connection with the optical fiber becomes easy.
Further, by patterning the guide groove and the optical waveguide in the same step, the alignment between the optical fiber and the optical waveguide can be easily and accurately performed. Furthermore, the optical filter and the half mirror are inserted into slits formed obliquely in the optical waveguide on the substrate, and the light of the corresponding wavelength is reflected toward the light receiving element on the substrate or the light from the light emitting element on the substrate is reflected. By adopting a configuration in which light is reflected toward the optical fiber via the optical waveguide, a general surface light receiving type that does not require high positioning accuracy can be used as the photodiode as the light receiving element. In addition, by providing a spacer between the substrate and the light receiving element or the light emitting element to adjust the distance between the optical filter and the light receiving element or the light emitting element as needed, the size of the filter, the light receiving element or the light emitting element can be increased. Irrespective of the arrangement, the light receiving or light emitting position can be adjusted without processing them, so that the versatility is improved and the assembly is simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical transceiver module to which the present invention is applied. ,

FIG. 2 is a sectional view of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a view similar to FIG. 3, showing a modification of the optical transceiver module to which the present invention is applied;

FIG. 5 is a perspective view showing an example of a structure of a spacer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Step part 2 Connection part 2a Guide groove 3 First receiving part 4 Transmitting part 5 Second receiving part 6 Optical waveguide 6a Lower cladding layer 6b Core layer 6c Upper cladding layer 7 Reflective optical filter 8 Photodiode 9 Half Mirror 10 Photodiode 11 Laser diode 12 Monitor photodiode 13a, 13b Groove 15 Spacer 15a Cavity F Optical fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/02 F term (Reference) 2H037 AA01 BA02 BA11 BA24 CA37 CA38 DA04 DA06 DA12 2H047 KA04 KB08 LA14 LA18 MA05 PA05 PA06 PA24 QA02 RA08 TA05 TA31 TA42 TA43 5F073 AB21 AB28 BA02 FA05 FA07 FA13 FA15 FA23 5K002 AA05 AA07 BA02 BA13 BA14 BA21 BA33 DA04 FA01

Claims (6)

[Claims] An optical transceiver module for transmitting and receiving an optical signal of a first wavelength transmitted by an optical fiber and receiving an optical signal of a second wavelength, wherein the quartz module guides an end of the optical fiber. An optical fiber guide groove formed on a substrate made of silicon (Si); an optical waveguide formed on the substrate so as to match an end of an optical fiber guided by the optical fiber guide groove; A light-emitting element for the light of the first wavelength disposed on a substrate; a light-receiving element for the light of the first and second wavelengths disposed on the substrate; and light from the optical fiber to the optical waveguide. An optical filter disposed in the optical waveguide on the substrate so as to split the light into the light of the first wavelength and the light of the second wavelength; and a first wavelength split by the optical filter. Light of the first wavelength And a half mirror disposed in the optical waveguide on the substrate to guide the light of the first wavelength from the light emitting element from the optical waveguide to the optical fiber. Optical transceiver module. 2. The optical filter is inserted into a slit formed obliquely in the optical waveguide on the substrate,
The optical transceiver module according to claim 1, wherein the light of the second wavelength is reflected toward a light receiving element on the substrate. 3. The half mirror is inserted into a slit formed obliquely in the optical waveguide on the substrate, and the light of the first wavelength demultiplexed by the optical filter on the substrate. 2. The optical fiber according to claim 1, wherein the light is reflected toward a light receiving element and light of a first wavelength of the light emitting element is guided from the optical waveguide to the optical fiber.
Alternatively, the optical transceiver module according to claim 2. 4. The substrate according to claim 1, wherein said substrate is made of a silicon substrate, and said guide groove is formed so as to form a V-shaped cross section by anisotropic etching. An optical transmitting / receiving module according to any one of the above. 5. A light-transmitting spacer is provided between the substrate and the light-receiving element or the light-emitting element in order to adjust a distance between the optical filter and the light-receiving element or the light-emitting element. The optical transceiver module according to any one of claims 1 to 4, wherein: 6. The optical transceiver module according to claim 1, wherein the optical filter and the half mirror are embedded inside the substrate so as not to protrude from the substrate surface. .